EDIT: Duplicate of MC-183769, which is duplicated by MC-176755 and MC-183779.

Starting a Minecraft server on 20w20a with the officially provided server.jar, both by downloading it from the launcher and from https://minecraft.net yields the following error log:

[18:22:16] [main/ERROR]: Unable to bootstrap registry 'minecraft:entity_type'
[18:22:16] [main/ERROR]: Unable to bootstrap registry 'minecraft:feature'
Exception in thread "main" java.lang.ExceptionInInitializerError
       at gl.H(SourceFile:94)
       at gl.a(SourceFile:132)
       at java.base/java.util.LinkedHashMap$LinkedEntrySet.forEach(LinkedHashMap.java:671)
       at gl.<clinit>(SourceFile:131)
       at aoc.a(SourceFile:144)
       at aoc.<clinit>(SourceFile:150)
       at ckx.<clinit>(SourceFile:23)
       at cka.<clinit>(SourceFile:64)
       at cqg.<clinit>(SourceFile:77)
       at cif.<clinit>(SourceFile:64)
       at net.minecraft.server.MinecraftServer.<clinit>(SourceFile:179)
Caused by: java.lang.NullPointerException
       at bsh.<init>(SourceFile:44)
       at bqk.<clinit>(SourceFile:9)
       ... 11 more

There are no crash-reports generated, and the latest.log file only shows the two first lines of the above message.